Insertion instrument for intervertebral implants

ABSTRACT

An insertion tool for positioning intervertebral spacers into disc spaces. The insertion tool has a proximal end and a distal end, a T-handle secured to the proximal end and a pair of alignment rails extending to the distal end. The insertion tool includes a handle secured to the proximal end of the guide rails, and a shaft that extends through the handle, whereby the shaft has a threaded portion that extends to the T-handle. The insertion tool also includes a blocker that is secured to the distal end of the shaft. The blocker includes stop arms that guide the blocker through the guide rails and toward the distal end of the shaft. The blocker may be provided in a plurality of different sizes corresponding to the sizes of the implants to be inserted into a disc space. A lock is provided for locking the implant to the shaft.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/321,258, filed on Jul. 1, 2014, which is a continuation of U.S.patent application Ser. No. 12/228,251, now U.S. Pat. No. 8,801,758,filed on Aug. 11, 2008, which claims the benefit of the filing date ofU.S.

Provisional Patent Application No. 60/964,624 filed Aug. 13, 2007, thedisclosures of which are hereby incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to spinal stabilization and moreparticularly relates to systems and tools for inserting implants intointervertebral disc spaces.

BACKGROUND OF THE INVENTION

There have been many recent developments in the field of spinalstabilization. In some instances, plates are used to stabilize spinalsegments. In other instances, however, pedicle screws and stabilizingrods are utilized for stabilizing spinal segments. More recently, therehave been a number of advances using implants placed into disc spacesbetween vertebral bodies. These advances also involve the use of toolsfor preparing the disc space and inserting the implants.

In spite of the above advances, there remains a need for improvedmethods and tooling for stabilizing spinal segments.

SUMMARY OF THE INVENTION

In certain preferred embodiments, the present invention provides aninsertion tool for positioning intervertebral spacers into disc spaces.In certain preferred embodiments, the present invention discloses aninsertion tool having a proximal end and a distal end, a T-handlesecured to the proximal end and a pair of alignment rails extending tothe distal end. The insertion tool includes a handle secured to theproximal end of the guide rails, and a shaft that extends through thehandle, whereby the shaft has a threaded portion that extends to theT-handle. The insertion tool also includes a blocker that is secured tothe distal end of the shaft. The blocker includes stop arms that guidethe blocker through the guide rails and toward the distal end of theshaft. The blocker may be provided in a plurality of different sizes, inresponse to the size of an implant to be inserted into a disc space. Animplant may be secured to the blocker and advanced toward the distal endof the tool using the shaft and the blocker.

In certain preferred embodiments, the shaft has a bore extending fromthe proximal end to the distal end thereof. An internal locking shaftmay be extendible through the bore of the shaft for selectively securingthe implant to the blocker.

In one aspect the present invention provides an intervertebral implantinsertion instrument having a first handle having a first end and asecond end. A second handle is located towards the first end andconnected to the first handle. A pair of rails is attached to the secondend of the first handle. A shaft having a third end and a fourth endthreadably engages the first handle. A blocker is attached to the fourthend of the shaft. The blocker is adapted to accept a fifthintervertebral implant such that when the fifth intervertebral implantis advanced towards the vertebrae the rails do not contact the fifthimplant.

In another aspect the present invention teaches a method of implantingan intervertebral implant. The method includes the steps of: inserting adistal end of an intervertebral implant insertion instrument between twovertebrae, the implant insertion instrument including a first handle anda second handle; attaching a blocker to the implant insertioninstrument; attaching an implant to the blocker, the implant having atop and a bottom surface; and sliding the implant along a guide path onthe implant insertion instrument and between the vertebrae without thetop and surfaces of the implant being contacted by the implant insertioninstrument.

These and other preferred embodiments of the present invention will bedescribed in more detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B show perspective views of an insertion tool for anintervertebral implant, in accordance with certain preferred embodimentsof the present invention.

FIG. 2 shows a proximal end of the insertion tool shown in FIGS. 1A and1B.

FIG. 3 shows another view of the proximal end of the insertion toolshown in FIG. 2 including a T-handle, a sleeve and a handle.

FIGS. 4A and 4B show an expanded view of the T-handle at the proximalend of the insertion tool shown in FIG. 3.

FIG. 5 shows a cross-sectional view of the T-handle at the proximal endof the insertion tool shown in FIG. 3.

FIGS. 6A and 6B show a cross-sectional view of the sleeve a portion ofthe insertion tool shown in FIG. 3.

FIG. 6C shows another cross-sectional view of the sleeve portion of theinsertion tool shown in FIG. 3.

FIGS. 7A-7C show a blocker used in conjunction with the insertion toolshown in FIGS. 1A and 1B, in accordance with certain preferredembodiments of the present invention.

FIGS. 8A-8F show a plurality of blockers having different sizes, inaccordance with certain preferred embodiments of the present invention.

FIG. 9 shows a distal end of the insertion tool shown in FIGS. 1A and1B.

FIG. 10 shows another view of the distal end of the insertion tool shownin FIG. 9.

FIGS. 11A-11C show a method of assembling the blocker of FIG. 7A and animplant with the insertion tool of FIGS. 1A and 1B, in accordance withcertain preferred embodiments of the present invention.

FIGS. 12A and 12B show a method of assembling an implant with theblocker of FIG. 7A and the insertion tool of FIGS. 1A and 1B, inaccordance with certain preferred embodiments of the present invention.

FIGS. 13A-13C show a method of advancing an implant toward a distal endof the insertion tool shown in FIGS. 1A and 1B, in accordance withcertain preferred embodiments of the present invention.

FIGS. 14A-14H show a method of inserting an implant between vertebrae,in accordance with certain preferred embodiments of the presentinvention.

FIGS. 15 and 16A-16B show a method of unlocking an implant lock at aproximal end of the insertion tool shown in FIGS. 1A and 1B, inaccordance with certain preferred embodiments of the present invention.

FIGS. 17A and 17B show a method of uncoupling an implant from a distalend of the insertion tool shown in FIGS. 1A and 1B, in accordance withcertain preferred embodiments of the present invention.

FIGS. 18A-18B show perspective views of an insertion tool for anintervertebral implant, in accordance with other preferred embodimentsof the present invention.

FIG. 18C shows a side view of the insertion tool shown in FIGS. 18A-18B.

DETAILED DESCRIPTION

Referring to FIGS. 1A and 1B, in one preferred embodiments of thepresent invention, an insertion tool 100 has a proximal end 102 and adistal end 104. The insertion tool 100 includes a rotatable I-handle 106having an implant lock 108 movable between a locked position and anunlocked position. The I-handle 106 is coupled with a shaft 110 thatextends from the I-handle, through a sleeve 112 and a handle 114, andtoward the distal end 104 of the insertion tool 100. The handle 114 thatis located between the sleeve 112 and a pair of guide rails 116A, 116Bthat are pivotally connected to the distal end of the handle. As aresult of the pivot connections, the distal ends of the guide rails areable to move away from one another for distracting a disc space. Theinserter 100 also includes blocker 118 that may be coupled with a distalend of the shaft 110.

The proximal end of the shaft 110 has external threads that mesh withthe sleeve 112 for moving the shaft proximally or distally relative tothe sleeve. The distal end of the shaft 110 is non-threaded. As will bedescribed in more detail below, the shaft 110 has a central bore that isadapted to receive an internal locking shaft used to couple an implantwith a distal end of the insertion tool.

FIG. 2 shows the T-handle 106 connected with the threaded portion of theshaft at the proximal end of the shaft. The T-handled 106 may be rotatedin a first direction for advancing the shaft 110 toward the distal endof the tool, and in a second opposite direction for retracting the shafttoward the proximal end of the tool. The T-handle 106 may be rotated inthe first direction until the sleeve 112 is fully received within theT-handle as shown in FIG. 3.

Referring to FIG. 3, the sleeve 112 includes a depressible button 120that may be depressed when it is desirable to disengage the sleeve fromthe threads on the shaft 110 for quickly advancing the T-handle 106 andthe shaft 110 toward the distal end of the insertion tool 100.

FIGS. 4A and 4B show an implant lock 108 that is used for securing animplant to a distal end of the shaft 110. FIG. 4A shows the implant lock108 in the unlocked position. FIG. 4B shows the implant lock 108 afterit has been advanced into the locked position. As noted above, theimplant lock 108 is moved between the unlocked and locked positions forselectively securing an implant to a distal end of the shaft 110.

FIG. 5 shows a partial cross-sectional view of the insertion toolincluding the I-handle 106 connected with a proximal end of the shaft110. As shown in FIG. 5, the shaft 110 is hollow and includes aninternal locking shaft 122 provided therein. The internal locking shaft122 is coupled with the implant lock 108 and is slideable along thelongitudinal axis of the shaft 110. The implant lock 108 includes a pairof pins 124 that extend between an upper tab 126A and a lower tab 126B.The pins 124 engage an undercut 128 formed adjacent the proximal end ofthe internal locking shaft. The T-handle 106 is secured to the proximalend of the shaft 110 so that the T-handle and the shaft rotate together.The internal locking shaft 122 is not designed to rotate with theT-handle 106. The internal locking shaft 122 is designed to beselectively moved along the longitudinal axis of the shaft 110 formoving the internal locking shaft between an advanced locking positionand a retracted unlocking position. As the T-handle 106 is rotated, thepins 124 of the implant lock 108 rotate about the undercut 128 on theinternal locking shaft 122.

FIGS. 6A and 6B show a partial cross-sectional view of the insertiontool 100 including the depressible threaded shaft button 120. In thenormal position shown in FIG. 6A, the sleeve 112 is coupled with thethreaded section of the shaft 110 via spring element 130 and nubs 132,the latter elements engaging the threads 111 of the shaft 110. As theshaft 110 is rotated, the sleeve 112 may be advanced toward the proximalor distal end of the tool.

FIG. 6B shows the depressible threaded shaft button 120 after it hasbeen depressed. As a result of the depression of the threaded shaftbutton 120, the spring element 130 is compressed so that the nubs 132are disengaged from the threads 111. As a result, the sleeve 112 may berapidly advanced in either direction along the longitudinal axis A₁ ofthe shaft 110. For example, the button 120 may be depressed to quicklyadvance the distal end of the shaft 110 toward the distal end of theinstrument 100.

FIG. 6C shows the depressible threaded shaft button 120 provided on thesleeve 112 and disposed between the I-handle 106 and the handle 114.When the button 120 is depressed, the sleeve 112 and the handle 114 maybe quickly slid toward the distal end of the insertion instrument. Whenthe depressible button 120 is released, and allowed to return to itsnormal position shown in FIG. 6C, the sleeve 112 is reengaged with thethreads 111 on the shaft 110 and may only be advanced further byrotating the I-handle 106. At this point, the sleeve 112 is reengagedwith the threaded shaft.

FIGS. 7A, 7B and 7C show a blocker 118, in accordance with certainpreferred embodiments of the present invention. The blocker 118 ispreferably attached to the distal end of the shaft 100. The blocker 118includes a proximal end 134 and a distal end 136 having a concave face138 adapted to seat an implant. The blocker 118 includes a top surface140 having a first depression 142 formed therein and a bottom surface144 having a second depression 146 formed therein. The blocker 118includes a spring collet 148 projecting from the concave face 138. Thespring collet 148 includes a plurality of spaced fingers 150 that arecompressible toward one another. The fingers 150 may also be flexed awayfrom one another due to advancement of the internal locking shaft [notshown] toward the distal end of the tool.

The blocker 118 also includes an offset element 152 including a firststop arm 154 projecting above the top surface 140. The first stop arm154 has an undercut 155 not shown in FIGS. 7A, 7B shown in FIG. 7C. Theblocker 118 includes a second stop arm 156 projecting below the bottomsurface 144. The second stop arm also has an undercut 157.

The blocker 118 also includes an adjustment knob 158 that may be engagedfor moving the stop arms 154, 156 between the proximal and distal endsthereof. The adjustment knob 158 enables the blocker 118 to be set atdifferent offset distances from 0 MM to 6 MM so that the depth of theimplant from an outer edge of an intervertebral disc space may be set.FIG. 7C shows a cross-sectional view of the blocker 118 shown in FIGS.7A and 7B. The blocker 118 includes proximal end 134 and distal end 136including concave face 138. The spring collet 148 extends from theconcave face 138. The blocker 118 includes offset adjustment elements152 that may be moved between the proximal and distal ends of theblocker by rotating the thumb screw 158. As the thumb screw 158 isrotated, a threaded shaft 160 attached to the thumb screw 158 is alsorotated. The threaded shaft 160 engages the adjustment element 158,which, in turn, is connected with the stop arms 154 and 156.

Referring to FIGS. 8A-8F, in certain preferred embodiments of thepresent invention, a plurality of blockers 118 are provided. Eachblocker has a height that extends between the top surface 140 and thebottom surface 144 thereof. FIGS. 8A-8F show a plurality of blockershaving different heights. For example, the blocker 118B shown in FIG. 8Bhas a greater height than the blocker 118A shown in FIG. 8A. In turn,the blocker 118C shown in FIG. 8C has a greater height than the blocker118B shown in FIG. 8B. Each blocker has a size or height that thespecifically designed to accommodate a particular implant height. In theparticular preferred embodiment shown in FIGS. 8A-8F, the blockers areassociated with implants having the following heights: blocker 118A inFIG. 8A is for a 10 MM implant, blocker 118B in FIG. 8B is for a 12 MMimplant, blocker 118C in FIG. 8C is for a 14 MM implant, blocker 118D inFIG. 8D is for a 16 MM implant, blocker 118E in FIG. 8E is for an 18 MMimplant, and blocker 118F in FIG. 8F is for a 20 MM implant.

FIG. 9 shows the distal end 104 of the insertion instrument 100, inaccordance with certain preferred embodiments of the present invention.The distal end of the insertion instrument preferably includes a firstguide rail 116A and a second guide rail 116B. Referring to FIG. 10, thefirst guide rail 116A desirably includes a first slot 162A that extendsto the distal end 104 of the instrument. The second guide rail 116Bdesirably includes a second slot 162B that also extends toward thedistal end of the insertion instrument. Each of the guide rails 116A,116B includes a respective vertebral body stopper 164A, 164B thatprevents over insertion of the rails into a disc space between vertebralbodies.

The slots 162A, 162B in the respective rails 116A, 116B terminate beforethe distal-most end of the insertion tool so that the slots are closedat their distal ends 166. The distal ends 166 of the slots 162A, 162Bare adapted to halt advancement of the blocker beyond the distal end ofthe tool. The slots 162A, 162B are designed to receive the stop arms ofthe blocker (shown in FIG. 7C) for guiding the blocker towards thedistal end of the insertion tool. The guiding of the stop arms of theblocker in the slots 162A, 162B of the respective rails 116A, 116Bprovide stabilization for the blocker as the blocker is moved toward thedistal end of the insertion tool.

FIG. 11A shows the distal end of shaft 110, which has a shaft springcollet 170 projecting therefrom. The shaft spring collet 170 includes aplurality of spaced fingers 172 that are adapted to flex relative to oneanother. The fingers may be compressed toward one another or expandedaway from one another in response to forces. FIG. 11A also shows adistal end of the internal locking shaft 122, which projects from theshaft spring collet 170 and the distal end of the shaft 110. Referringto FIG. 11B, one of the blockers 118 shown and described above may besecured to the distal end of the shaft 110. In certain preferredembodiments, the securing may be accomplished by inserting the shaftspring collet 170 into a bore extending through blocker 118. The borepreferably extends from a proximal end to a distal end of the blocker.The internal locking shaft 122 may then be advanced to expand thefingers 172 of the shaft spring collet 170 to secure the blocker to thedistal end of the shaft 110.

Referring to FIG. 11C, after the blocker 118 is secured to the distalend of the shaft 110, an implant 174 may be secured to the blocker 118.The blocker spring collet 148 and the internal locking shaft 122 arepreferably inserted into a bore at a trailing end of the implant 174 forsecuring the implant with the blocker 118.

FIGS. 12A and 12B show the implant 174 being secured to the distal endof the blocker 118. Referring to FIGS. 11A and 12A, in order to securethe blocker 118 with the distal end of the shaft 110, the shaft springcollet 170 and the distal end of the internal locking shaft 122 areinserted into the bore 176 extending through the blocker 118. As theinternal locking shaft 122 advances through the shaft spring collet 170,the flexible fingers 172 of the shaft spring collet 170 expand outwardlyfor engaging the internal walls of the bore 176 of the blocker 118. Theoutward expansion of the fingers 172 locks the blocker 118 to the distalend of the shaft 110.

Referring to FIGS. 12A and 12B, after the blocker 118 has been securedto the distal end of the shaft, one of the implant 174 may be secured tothe distal end of the blocker 118. In one preferred embodiment, theblocker has a blocker spring collet 148 that is inserted into a bore 178provided in the trailing end of the implant 174. As shown in FIG. 12B,the internal locking shaft 122 is advanced toward the distal end of theinsertion tool so that the internal locking shaft 122 expands theflexible fingers 150 of the blocker spring collet 148. The outwardexpansion of the flexible fingers 150 secures the implant 148 to theblocker 118. The locking action is preferably obtained by the flexiblefingers 150 engaging the inner wall surrounding bore 178. In preferredembodiments, the implant is secured to the blocker during insertion ofthe implant into an intervertebral disc space. After insertion of theimplant into the disc space, the internal locking shaft 122 is retractedfor releasing the implant from the blocker 118.

FIGS. 13A-13C show the insertion tool 100 after the blocker 118 has beensecured to the distal end of shaft 110 and the implant 174 has beensecured to the blocker 118.

As shown in FIG. 13A, the slots 162A, 162B provided in the respectiveguide rails 116A, 116B guide the blocker 118 and the implant 174 towardthe distal end of the insertion tool 100. The first stop arm 154 on theblocker 188 slides through the first slot 162A for guiding advancementof the blocker 118 toward the distal end of the tool. Although not shownin FIG. 13A, a second stop arm (projecting from the bottom of theblocker) guides advancement of the blocker through the second slot 162B.

FIGS. 13B and 13C show the position of the implant 174 and the blocker118 after the implant and blocker have been moved to the distal end ofthe first and second guide rails 116A, 116B. As shown in FIG. 13C, thefirst stop arm 154 has an undercut 155 that engages an end wall at thedistal-most end of the first slot 162A. The second stop arm 156 alsoincludes an undercut that engages an end wall at the distal-most end ofthe second slot (not shown). Each stop arm 154, 156 has a distal face180A, 180B that is adapted to engage outer surfaces of vertebral bone.When the distal end faces 180A, 180B engage the vertebral bone, furtherdistal advancement of the implant 174 into the disc space is halted.

Referring to FIGS. 14A-14H, in one preferred embodiment of the presentinvention, an implant 174 may be inserted into a disc space betweenvertebral bone. Referring to FIG. 14A, the implant 174 and the blocker118 may be secured to a distal end of the shaft 110 using the structureand methods described above. As shown in FIG. 14A, the implant 174 andthe blocker 118 are positioned between first guide rail 116A and secondguide rail 116B. As the blocker 118 and the implant 174 are advancedtoward the distal end 104 of the insertion instrument 100, the top andbottom surfaces of the blocker 118 engage the opposing inner surfaces ofthe first and second guide rails 116A, 116B. As a result, all of theforces required for separating the guide rails during a distractionoperation are exerted upon the blocker 118 and not the implant 174. Theblocker 118 thereby prevents the distraction forces from being exertedupon the implant 174, which may damage the implant.

Referring to FIG. 14B, the distal ends of the respective guide rails116A, 116B are inserted into a disc space between opposing vertebrae190A, 190B. Referring to FIG. 14C, the guide rails 116A, 116B areadvanced until the vertebral body stops 164A, 164B abut against outersurfaces of the opposing vertebrae 190A, 190B.

Referring to FIG. 14D, after the distal ends of the opposing rails 116A,116B have been inserted between the vertebral bodies 190A, 190B, theshaft 110 is advanced toward the distal end of the insertion tool. Theshaft may be advanced using the structure described above. As the shaft110 advances toward the distal end of the insertion tool, the shaft 110in turn urges the blocker 118 and the implant 174 toward the distal endof the insertion tool.

Referring to FIG. 14E, the blocker 118 provides the distraction forcefor distracting the disc space between the vertebrae 190A and 190B. Theblocker 118 urges the implant 174 into the disc space until the distalfaces of the stop arms 154, 156 abut against the outer surfaces of thevertebral bodies. At this point, the implant 174 has been fully insertedbetween the vertebral bodies.

FIGS. 14F-14H show steps for retracting the distal ends of the guiderails 116A, 116B from their placement between the vertebral bodies.Referring to FIG. 14F, while pressing the stop arms 154 and 156 againstthe vertebral bodies, the guide rails 116A, 116B are retracted relativeto the shaft 110. FIG. 14G shows further retraction of the guide rails116A, 116B relative to the shaft 110. As the guide rails 116A, 116B areretracted relative to the shaft 110, the stop arms 154 and 156 remainpressed against the vertebral bodies.

Referring to FIG. 14H, the internal locking shaft (not shown) isretracted toward the proximal end of the tool so that the blocker 118may be released from the implant 174. As the internal locking shaft isretracted, the resilient fingers on the blocker spring collet 148 areable to flex inwardly toward one another so as to release the implant174 from the blocker 118.

FIGS. 15-16B show a subassembly for automatically releasing the implantfrom the insertion tool, in accordance with certain preferredembodiments of the present invention. The subassembly includes a sleevethat may be retracted into the T-handle for engaging the implant lockand moving the implant lock into an unlocked position. As the implantlock is moved into an unlocked position, it in turn retracts theinternal locking shaft for releasing an implant from the blocker.

Referring to FIG. 15, the insertion tool 100 includes the I-handle 106mounted to the proximal end of the tool. The I-handle includes theimplant lock 108 having pins 124 coupled with the proximal end of theinternal locking shaft 122. In FIG. 15, the implant lock 108 is in thelocked position. As a result, the internal locking shaft 122 is fullyextended toward the distal end of the insertion tool 100 so that animplant may be secured to the tool. The insertion tool includes thesleeve 112 extending from a proximal end of the handle 114.

Referring to FIGS. 15 and 16A, as the I-handle 106 is rotated, thesleeve 112 moves toward the proximal end of the insertion tool in thedirection D₁. As the sleeve 112 is retracted toward the I-handle, aleading edge of the sleeve 112 moves closer to the pins 124 of theimplant lock 108.

Referring to FIG. 16B, further retraction of the sleeve 112 eventuallyresults in the proximal end of the sleeve engaging the pins 124 andurging the pins 124 toward the proximal end of the insertion tool. Thisretracting movement causes the implant lock 108 to move from the lockedposition shown in FIG. 15 to the unlocked position shown in FIG. 16B. Asthe pins 124 move toward the proximal end of the insertion tool, thepins engage the undercut 128 in the internal locking shaft 122 forretracting the internal locking shaft 122 toward the proximal end of theinsertion tool.

FIGS. 17A and 17B show the distal end of the insertion tool as thesleeve shown in FIG. 16B is retracted toward the proximal end of theinsertion tool. Referring to FIGS. 16B and 17A, when the sleeve isretracted to the position shown in FIG. 16B, the implant lock 108 beginsto urge the internal locking shaft 122 toward the proximal end of thetool. In response, as shown in FIG. 17A, the distal end of the internallocking shaft is retracted into the blocker 118. As the distal end ofthe internal locking shaft 122 is retracted, the flexible fingers of theblocker spring collet 148 are able to flex inwardly for releasing theimplant 174 from the blocker 118.

FIG. 17B shows implant 174 after it has been detached from the blockerspring collet 148 at the distal end of blocker 118.

FIGS. 18A-18C show an insertion tool, in accordance with other preferredembodiments of the present invention. The insertion tool 200 includesfirst and second guide rails 216A, 216B for guiding an implant toward adistal end of the tool. In one preferred embodiment, the second guiderail 216B includes a protective hood 225 defining a channel 227 throughwhich the second stop arm 256 on the blocker 218 is advanced toward thedistal end of the tool. The protective hood 225 may have a curvedexterior surface. The protective hood is desirably adapted forprotecting nerves and soft tissue adjacent the spine as the implant isinserted between vertebrae. The protective hood may prevent the stoparms on the blocker from contacting the above-mentioned nerves and softtissue. In certain preferred embodiments, the protective hood is onlyprovided on one of the guide rails (e.g. either the first guide rail216A or the second guide rail 216B). In other preferred embodiments, aprotective hood may be provided on each of the guide rails.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

1. An intervertebral implant insertion instrument comprising: a firsthandle having a first end and a second end; a second handle locatedtowards the first end and connected to the first handle; a pair of railsattached to the second end of the first handle; a shaft threadablyengaging the first handle, the shaft having a third end and a fourthend; a blocker attached to the fourth end of the shaft, the blockerbeing adapted to accept a fifth intervertebral implant such that whenthe fifth intervertebral implant is advanced towards the vertebrae therails do not contact the fifth implant.